A study explored how effective interior insulation systems are at keeping basements dry as well as warm.

In 2001,Cambridge Homes—a division of D.R.Horton in the Chicago area—completed the initial phase of its first Energy Star development. One of the builder’s major improvements of these homes was the insulation of the basement walls.While the homes met the Energy Star goals, problems arose during the first summer the homes were occupied. During a hot, humid period in August, several homeowners reported wet, dripping fiberglass insulation at the foot of their basement walls.Where this moisture came from (humid basement air condensing on the cold wall, drying concrete, groundwater or rain, or some combination of these factors) was unclear,but it certainly needed a remedy. One homeowner was so concerned that she called the EPA to report the problem. The builder knew that to reach Energy Star levels for homes, basement insulation was key. The insulation system that Cambridge employed was polymer-faced, R-11 fiberglass blankets draped inside the entire basement wall. The builder’s immediate solution to the moisture problems was to trim all of the fiberglass blankets 6–12 inches above the floor—eliminating the place where ...